Molecular Mechanisms of Curcumin on Diabetes-Induced Endothelial Dysfunctions: Txnip, ICAM-1, and NOX2 Expressions

We aim to investigate the effects of curcumin on preventing diabetes-induced vascular inflammation in association with its actions on Txnip, ICAM-1, and NOX2 enzyme expressions. Male Wistar rats were divided into four groups: control (CON), diabetic (DM; streptozotocin (STZ), i.v. 55 mg/kg BW), control-treated with curcumin (CONCUR; 300 mg/kg BW), and diabetes treated with curcumin (DMCUR; 300 mg/kg BW). 12th week after STZ injection, iris blood perfusion, leukocyte adhesion, Txnip, p47phox, and malondialdehyde (MDA) levels were determined by using laser Doppler, intravital fluorescent confocal microscopy, Western Blot analysis, and TBAR assay, respectively. The iris blood perfusion of DM and DMCUR was decreased significantly compared to CON and CONCUR ( P < 0.001). Plasma glucose and HbA1c of DM and DMCUR were increased significantly compared to CON and CONCUR ( P < 0.001). Leukocyte adhesion, ICAM-1, p47phox expression, and MDA levels in DM were increased significantly compared to CON, CONCUR, and DMCUR ( P < 0.05). Txnip expression in DM and DMCUR was significantly higher than CON and CONCUR ( P < 0.05). From Pearson's analysis, the correlation between the plasma MDA level and the endothelial functions was significant. It suggested that curcumin could ameliorate diabetic vascular inflammation by decreasing ROS overproduction, reducing leukocyte-endothelium interaction, and inhibiting ICAM-1 and NOX2 expression.